Final answer:
The highest priority finding for a nurse assessing a client's peripheral circulation after cardiac catheterization is the client experiencing numbness in the toes.
Step-by-step explanation:
The highest priority finding for a nurse assessing a client's peripheral circulation after cardiac catheterization would be D. The client is experiencing numbness in the toes. This finding could indicate a potential complication called ischemia, which is a lack of blood supply to the tissues. Numbness in the toes suggests impaired circulation, and immediate medical attention is needed to prevent further damage or complications.